Process for preparing hydroxyalkyl esters

ABSTRACT

Hydroxyalkyl esters of acrylic and methacrylic acids are prepared using heterogeneous amorphous catalysts.

BACKGROUND OF THE INVENTION

This invention relates to the us of heterogeneous metal catalysts in theproduction of unsaturated hydroxyalkyl esters.

The catalyst art has long recognized the utility of certain phosphateand metal phosphate catalyst compositions. Among such materials arealuminum phosphates, both stoichiometric AlPO₄ and non-stoichiometricAl(PO₄)_(x) where x is less than 1. For instance, U.S. Pat. No.3,904,550 describes the preparation of such materials and their use asdesulfurization catalysts. U.S. Pat. No. 3,801,704 teaches that aluminumphosphates can be used for catalytic dehydration. U.S. Pat. No.4,524,225 demonstrates that such phosphates also function ashydrogenation catalysts. Other cited uses of aluminum phosphates includecracking (U.S. Pat. No. 4,382,878), ether rearrangement (U.S. Pat. No.4,538,008), and polyolefin synthesis (U.S. Pat. Nos. 4,364,839;4,547,479; 4,424,139; 4,397,765; 4,596,862; 4,504,638; and 4,364,854).In all of these cases stoichiometric or non-stoichiometric aluminumphosphates are taught and methods for making them described.

Among other phosphate-containing catalyst compositions described in theart are strontium compounds described in U.S. Pat. No. 4,505,784 asuseful for the synthesis of various amines and other nitrogen-containingcompounds.

Iron phosphates, usually both stoichiometric and crystalline, are alsowell known, but have none of the properties required for catalyst orcatalyst support applications. For instance, Tsuhako, et al., (NipponKagaku Kaishi, No. 2, 1980, pp. 176-180) describe the preparations andproperties of eight crystalline iron phosphates all of which arestoichiometric and have PO₄ /Fe ratios greater than 1.0. Leumann andLutz, (Galvanotechnik, Vol. 68, No. 8, 1977, pp. 715-719) among othershave described the "iron phosphates" which are produced in he treatmentof phosphate-containing wastewaters. Such materials are usuallystoichiometric FePO₄ and, again, are not catalytic materials.

The art has long recognized the utility of the addition of alkyleneoxides to acrylic or methacrylic acid, always in the presence ofappropriate inhibitors, to produce 2-hydroxyalkyl (meth)acrylates. Acatalyst is always required for this addition. Catalysts mentioned inthe art include ammonium salts((U.S. Pat. No. 3,059,024), ammonium ionexchange resins (British Patent No. 1003346), phosphonium salts (GermanPatent Nos. 2527116 and 2527117), and lithium, sodium and potassiumsalts of the (meth)acrylate anion (Japanese Patent No. 7251382; FrenchPatent 1556337; and U.S. Pat. No. 3,214,988). A number of transitionmetal catalysts, as salts, are also known to the art, including copper(U.S. Pat. No. 3,709,928), titanium (Japanese Patent 6902686), vanadium(Japanese Patent No. 8187537), niobium or ruthenium (U.S. Pat. No.4,223,160), chromium (U.S. Pat. No. 4,404,395), and iron (U.S. Pat. No.4,365,081).

Of these catalysts, the iron salts are the ones most frequently taughtin the art as catalyzing the production of 2-hydroxyalkyl(meth)acrylates from alkylene oxides and acrylic or methacrylic acid.The chromium salts are second most frequently taught in the art. BritishPatent No. 1003346, French Patents No. 1357422 and 1357423, U.S. Pat.Nos. 3,804,884 and 3,340,295, Belgian Patent Ser. No. 657517,Netherlands Patent No. 6700738, and Japanese Patent No. 7017662, all ofwhich teach the use of ion exchange resins as catalysts, teach the useof heterogeneous (that is, insoluble throughout the reaction) catalystsin the production of 2-hydroxyalkyl (meth)acrylates from alkylene oxidesand acrylic or methacrylic acid. Most often, the catalyst is soluble inthe reactants and the products, and a separation step of the productfrom the catalyst is required.

This discussion of the prior art is presented to show the variouscompositions and methods of preparing such compositions which are wellknown in the existing art, and to show the types of catalysts that arewell known in the existing art to promote the formation of2-hydroxyalkyl (meth)acrylates. These documents are only illustrative ofa large body of patents and articles, but the documents cited arebelieved to reflect the teachings most relevant to this invention.

SUMMARY OF THE INVENTION

The catalysts employed in this invention comprise non-stoichiometricphosphates of the following formula: M(PO₄)_(y) X'.

Thus, M⁺³ (PO₄)₁ is a stoichiometric metal phosphate, while M⁺³ ₁(PO₄)₀.5 is a non-stoichiometric metal phosphate. Since the valencerequirements of the metal M must be satisfied, these non-stoichiometriccompositions contain additional anionic species, OH⁻ and O²⁻. Suchcompositions also contain water, either coordinated to the metal andhence an integral part of the structure, or present simply as incidentalwater of hydration. The catalysts are uniform and amorphous in natureand, specifically, are not simply mixtures of phosphate and oxide and/orhydroxide compounds.

The surface characteristics of the catalysts of the present inventioncontribute to excellent catalytic performance. The pore volume, poresize distribution and surface area necessary to have active catalystsare produced by proper control of key variables in the preparationprocess. Thus, this invention provides specific process steps andconditions to achieve the desired results.

In general terms and using Fe⁺³ as a focus of discussion, the processfor preparing the catalysts can be carried out as follows. First anaqueous ferric solution is prepared from a suitable iron salt. Anappropriate phosphate source, e.g., orthophosphoric acid is then addedto the ferric solution. The resulting iron/phosphate solution is thenmixed with and reacted with a pH-adjusting medium, preferably analkaline solution such as dilute aqueous ammonia and the like to affectgelation or precipitation of the desired non-stoichiometric metal slurryphosphate composition. Other orders of mixing are permitted. The pH,concentration, temperature, and mixing time will influence thestoichiometyy and structure and hence the utility of the productobtained. The resultant slurry is then generally agitated for a periodof time to assure complete reaction. The solid is then separated fromthe liquid phase by conventional methods such as filtration orcentrifugation. Washing and drying may be done by any convenient means.The catalyst may now be formed into the appropriate shape and size.Finally, calcination may be conducted to remove excess water. Forming ofthe catalyst may, in some cases, be done most conveniently at an earlierstage, such as before washing or between washing and drying.

Catalysts of this invention have particular utility for certainindustrially important catalytic processes involving the esterificationof unsaturated carboxylic acids, in particular 2-hydroxyalkyl esters ofacrylic and methacrylic acids. The catalysts of this invention areheterogeneous catalysts for the production of these esters, and providean advantage because the separation of the catalyst from the pureproduct requires only a filtering step. The catalysts are highly activeand selective and provide unexpected advantages in the ease ofproduction and the purity of the product.

THE INVENTION

It has been found that certain inorganic nonstoichiometric metalphosphates have special utility as heterogeneous catalysts and comprisecompounds of the following formula:

    M(PO.sub.4).sub.y X'

Where M is a metal, preferably a transition metal with a +3 valence suchas Fe⁺³, Cr⁺³ and the like; y is the phosphate-to-metal mole ratio,which is in the range of from about 0.1 to 0.6 and preferably from about0.1 to 0.3, X' represents other anionic species to satisfy the valencerequirements of the metal.

The catalysts employed in this invention are also characterized by theiramorphous nature, that is there are no crystalline phases detected whenthese compositions are examined by conventional x-ray diffractionmethods. Further, the catalysts are uniform in nature in that separatephases of, for example, "FePO₄ " and Fe₂ O₃ or Fe(OH)₃ are not present.Additionally, the novel catalytic compositions having surface areas andpore volumes greater than 100 m² / g and 0.1 cc/g, respectively, aremost preferred.

The catalysts can be prepared as irregular powders or granules, but mostoften will be used as regular shapes such as microspherical beads,larger beads, or particles with cylindrical cross sections, as arecommonly used in heterogeneous catalysis. While these compositions canbe used without dilution or the use of a support, such dilution can bedesirable for economic reasons or to enhance the physical properties ofthe final product. Thus, inert inorganic materials, particularly oxidessuch as silica, alumina, titania and the like can be physically mixedwith the compositions at whatever stage of the preparation is mostconvenient. The inert "support" may be present at the point of gelationor precipitation. The level of diluent or support when employed mayrange from 10 to 90% w/w.

The process for preparing the catalysts comprises the following steps:

1. Preparing a dilute aqueous solution of an appropriate metal salt;

2. Preparing a dilute aqueous solution of an appropriate phosphate;

3 Mixing 1 and 2, and, if required, adding pH adjuster;

4. Aging the resultant product slurry;

5. Separating the solid catalyst composition from the slurry;

6. Washing the solid catalyst composition;

7. Drying;

8. Forming the catalyst into the desired size and shape particles;adding an inert diluent if desired; and

9. Calcining, if required,.

Each of these steps will now be considered in detail.

The metal salt may be any water-soluble salt of the metal desired whichhas the needed valence (oxidation state). Salts of strong acids areparticularly suitable. Thus, for example, ferric nitrate, ferric sulfateand ferric chloride are appropriate. In general, +3 oxidation statetransition metals produce the preferred catalytic properties --Fe⁺³,Cr⁺³, Ce⁺³, and the like are preferred transition metals. The metal saltsolution is usually dilute, having 1 to 10% solids by weight.

The phosphate solution may be prepared separately from the metal saltsolution, or may be prepared at the same time if the required PO₄ /Mmole ratio can be obtained without any reaction between the metal andphosphate. Suitable phosphate sources include orthophosphoric acid,ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogenphosphate and the like. This solution is also dilute, having 1 to 10%solids by weight. Mixing of these solutions is accomplished by anyconvenient means. Both can be added individually to a third pH-adjustingsolution, or the combined metal/phosphate solution can be added to thepH-adjusting solution. The mixing must be done efficiently withrelatively short mixing times to assure preparation of a homogeneousproduct.

The pH-adjusting solution is most conveniently dilute aqueous ammonia,but other alkaline materials may be suitable. The final pH of themixture should be 3 to 11; preferably 7 to 11; and most preferably 8 to1.

The mixing is usually carried out at ambient temperature, but atemperature as low as 0° C. and as high as 100° C. may enhance thephysical properties of the product. Aging for a period of 1 to 24 hoursat a temperature from about 25° C. to about 100° C. can also enhance thephysical properties of the product. Adjustment of pH or salt contentduring such aging also can provide improved properties.

Washing can be done by a decant-and-settle method or by washing on acentrifuge or filtration device. Washing is best done with deionized ordistilled water.

Drying is generally accomplished by conventional means such as forcedhot air, vacuum or spray drying. The temperature should be controlled toavoid decomposition of the catalyst composition. Temperatures less than200° C. are preferred.

Forming of the catalyst into the sizes and shapes of particles mostsuited to a particular application can be done by techniques well knownin the art. Thus, spray drying, extrusion, pelleting or variousspheroidization methods are effective. Inclusion of a diluent can bebeneficial. Forming or dilution can be done at various stages of thepreparation as dictated by the requirements of the specific formingmethod chosen. Suitable diluents well known in the art can be used, butsilica ha been found to be particularly suitable.

Finally, the preparation process can include a calcination step. Suchcalcination, normally in air but suitably done in other atmospheres suchas nitrogen or H₂ O-containing gases, will improve product strength andreduce the moisture content. Reducing moisture content is important froma catalytic standpoint, since H₂ O may participate in unwantednon-selective reactions. Calcination temperatures of 250°-400° C.produce the desired water loss without causing undesired changes incatalyst properties.

The invention relates to the use of catalysts for the esterification ofunsaturated carboxylic acids, especially the 2-hydroxyalkyl esters ofacrylic and methacrylic acids, from the acid and an appropriate alkyleneoxide, in particular, ethylene oxide o propylene oxide. The catalystsmay be used in any suitable reactor and may be used in batch orcontinuous processes. In a batch process the catalysts should be used atany effective level, usually from about 10 to about 70 wt % iron,preferably from 20 to 50 wt % iron, based on the initial weight of acidcharged. In a continuous process the instantaneous catalyst/liquidweight ratio will be in the corresponding range. The reactiontemperature is from about 30° to about 90° C., but preferably from about50° to about 70° C. The reaction is carried out in the presence ofsuitable polymerization inhibitors that are known in the art. Separationof the catalyst from the product is accomplished by any convenient meanssuch as filtration, decantation, or centrifugation. It is desirable torecycle the catalyst, once separated. Separation of the catalyst fromthe product is improved over the prior art since the catalyst isessentially insoluble in the product.

The catalysts may be used in any convenient particle size. For a slurryprocess, particle size may range from a few microns to severalmillimeters. For fixed bed processes, as are well known in the catalystart, particle size will normally be 1 to 10 mm. Factors other thanreactor design, i.e., fixed bed versus slurry, may also influence thechoice of particle size. Examples of such factors are diffusion,pressure drop or filterability, any of which may be important with aparticular feed/product/process combination.

The use of these catalysts provides an advantage over catalysts that areknown in the art for the production of 2-hydroxyalkyl esters of acrylicand methacrylic acids. The catalysts show higher selectivity for thedesired product as well as higher activity, with the advantage that thereaction may be run at lower temperatures. While the reactiontemperature can vary widely it will be lower than those required byprior art catalysts and will still be complete more quickly than whenrun in the presence of catalysts that are known in the art. Thisobviously lowers the energy required and is therefore a more economicalprocess.

EXAMPLES

The following examples illustrate certain embodiments of this invention.These examples are not provided to establish the scope of the invention,which is described in the disclosure and recited in the claims. Theproportions are in parts by weight (pbw) or percent by weight (%/wt)unless otherwise indicated.

EXAMPLE 1 Catalyst Preparation

A solution is prepared by dissolving 690g ferric sulfate hydrate and 75g of 85 % H₃ PO₄ in 3000 g of deionized water. That solution is addeddropwise to a well-stirred solution of 1468 g of 28% aqueous ammonia in12,450 g of deionized water. The final solution has a pH of 10. Theresultant flocculent brown precipitate is removed by filtration using aconventional vacuum filtration apparatus and washed with copiousquantities of deionized water until the pH of the filtrate is about 7.The solid product is removed from the filter, dried in a forced air ovenat 105° C. and ground to the desired particle size before evaluation.Analysis shows stoichiometry of this product to be:

    Fe(PO.sub.4).sub.0.2 O.sub.1.2 (OH).sub.1.2 (H.sub.2 O).sub.1.2 0.2H.sub.2 O

The ground, sized product has a surface area of 261 m² /g and a porevolume of 0.18 cc/g.

EXAMPLE 2 Solubility of Catalyst

The product's solubility is evaluated in acrylic acid (AA) andhydroxyethylacrylate (HEA). AA and HEA are examples of the feed andproduct, respectively, of an esterification process in which thecatalyst is useful. At 70° C. no solubility was observed in HEA and at70° C. a solubility of only about 100 ppm in AA was observed. This lowsolubility is most desirable for catalysts to be used in heterogeneousesterification processes. Even a relatively soluble catalyst would haveonly a limited life and would contaminate the product. Stoichiometriciron phosphates and oxides are very soluble in AA, HEA and similarorganic acids and esters.

EXAMPLE 3 Effect of Calcining

The product of Example 1 is calcined in air at 400° C. for two hours.The physical properties of the material are unchanged, but itssolubility in AA is further reduced to less than half that previouslyobserved.

To demonstrate the utility of the catalysts of this invention in theproduction of unsaturated esters, the following examples are presented.

EXAMPLE 4 Preparation of HEA

A 500 ml Fischer-Porter reactor bottle equipped with a stirring bar ischarged with the catalyst from Example 1 (2.8 g). Acrylic acid (2.0 g)is added and the reactor bottle is connected to a multiported reactorhead (67% iron). The reactor is pressure tested, then evacuated.Ethylene oxide (4.7 g) is added as a gas at room temperature to apredetermined pressure. Gas addition is halted and the reactor is healedto 50° C. and held at that temperature for 1 hour. The catalyst isstirred in the solution throughout. The reactor is cooled to roomtemperature and the excess ethylene oxide is vented. A 20-minutenitrogen sparge of the product/catalyst mixture ensures additionalremoval of unreacted ethylene oxide. The mixture is filtered to removecatalyst and the resulting 2-hydroxyethylacrylate (HEA) is analyzed. Theresults, among those of ensuing examples, are presented in Table 1.

                  TABLE 1                                                         ______________________________________                                        HEA Analyses from Examples 4,8,9,10,12 and 13                                 (wt %)                                                                        Example   AA     HEA         EGDA  DEGMA                                      ______________________________________                                        4         2.28   85.0        0.05  4.39                                       8         1.94   89.3        0.05  5.04                                       9         2.72   84.7        0.05  5.76                                       10        1.33   90.6        0.05  5.73                                       12        3.29   78.1        0.10  7.14                                       13        33.60  39.6        0.12  6.58                                       ______________________________________                                         AA = Acrylic Acid                                                             HEA = Hydroxyethyl Acrylate                                                   EDGA = Ethyleneglycol Diacrylate                                              DEGMA = Diethyleneglycol Monoacrylate                                    

EXAMPLE 5

The procedure of Example 4 is repeated, except with less catalyst (1.9g, 46% iron), with methacrylic acid (2.0 g) used in place of acrylicacid, and slightly less ethylene oxide added (3.8 g). The reactor isheated to 70° C. for 1 hour. The results for the producthydroxyethylmethacrylate (HEMA) are presented in Table 2.

                  TABLE 2                                                         ______________________________________                                        HEMA Analyses from Examples 5 and 11                                          (area %)                                                                      Example  MAA     HEMA       EGDMA  DEGMMA                                     ______________________________________                                        5        2.31    76.2       1.34   3.65                                       11       3.70    86.8       0.17   3.17                                       ______________________________________                                         MAA = Methacrylic Acid                                                        HEMA = Hydroxyethyl Methacrylate                                              EGDMA = Ethyleneglycol Dimethacrylate                                         DEGMMA = Diethyleneglycol Monomethacrylate                               

EXAMPLE 6

The procedure of Example 4 i repeated, except propylene oxide (6.7 g) isused in place of ethylene oxide. Since propylene oxide is a volatileliquid at room temperature, it is chilled to ice temperature, then addedto the reactor by gas-tight syringe after the evacuation step. Thenitrogen sparge time is increased to 1 hour to ensure removal ofunreacted propylene oxide from the product solution. The results for theproduct hydroxypropylacrylate (HA) are presented in Table 3.

                  TABLE 3                                                         ______________________________________                                        HP(M)A Analyses from Examples 6 and 7                                         (area %)                                                                      Example (M)AA    HP(M)A    PGD(M)A DPGM(M)A                                   ______________________________________                                        6       6.85     60.79     0.27    1.92                                       7       4.48     91.40     0.34    --                                         ______________________________________                                         (M)AA = (Meth)acrylic Acid                                                    HP(M)A = Hydroxypropyl (Meth)acrylate                                         PGD(M)A = Propyleneglycol Di(meth)acrylate                                    DPGM(M)A = Dipropyleneglycol Mono(meth)acrylate                          

EXAMPLE 7

The procedure of Example 6 is repeated, except methacrylic acid (2.0 g)is used in place of acrylic acid, and the reaction is carried out for 1hour at 70° C. The results for the product hydroxypropyl (meth)acrylate(HPMA) are presented in Table 3.

EXAMPLE 8

A 500 ml Fischer-Porter reactor bottle is equipped with a stirring barand charged with the catalyst from Example 1 (72.9 g). Acrylic acid(100.0 g) and inhibitors are added and the reactor bottle is connectedto a multiported reactor head (35% iron). The reactor is pressuretested, evacuated, then filled with 5% oxygen in nitrogen to 10 psig atroom temperature. Ethylene oxide (72 g) is added as a liquid at thereaction temperature (50° C.), never exceeding 30psig in the reactor.The addition of the ethylene oxide occurs over approximately 1 hour, andthe reactor remains at temperature another 2 hours. The catalyst issuspended in the stirred solution throughout the experiment. The reactoris vented, and the reactor is sparged with nitrogen for 30 minutes asthe reactor is cooled to room temperature. The product is decanted fromthe catalyst and the resulting 2-hydroxyethylacrylate (HEA) is analyzed.The results presented in Table 1 are similar to those obtained for thesmaller scale reaction, example 1 except the yield of HEA is somewhathigher.

EXAMPLE 9

The procedure of Example 8 is repeated reusing the same catalystrecovered in Example 8. The results presented in Table 1 indicate thecatalyst is effective when reused.

EXAMPLE 10

The procedure of Example 8 repeated reusing the catalyst recovered inExample 9, which was washed with methanol and dried prior to this use.The results presented in Table 1 suggest that the catalyst when washedwith methanol and reused is as effective as a fresh catalyst.

EXAMPLE 11

The procedure of Example 10 is repeated, except with methacrylic acid(100.0 g) used in place of acrylic acid. The reactor is heated to 70° C.The results for the product hydroxyethylmethacrylate (HEMA) arepresented in Table 2.

EXAMPLE 12

As an example that the catalysts of this invention result in animprovement in product purity over a typical homogeneous catalyst taughtin the art for the production of HEA, the procedure of Example 4 isfollowed with FeCl₃ (0.029 g, 0.5% iron) as catalyst. The reactor isheated to 65° C. for 2 hours. The results for the producthydroxyethylacrylate (HEA) presented in Table 1 show that the catalystsof our invention are superior to those of the prior art. The yield ofthe desired product is higher and produced at a lower temperature andshorter time.

EXAMPLE 13

As an example that the catalysts of this invention are significantlydifferent from stoichiometric, commercially available iron phosphate,the procedure of Example 4 is followed with FePO₄ - H₂ O (1.9 g, 19.5%iron) as the catalyst for the reaction of acrylic acid (3.0) andethylene oxide (4.6 g). The reactor was heated to 65° C. for 2 hours.The results for the product hydroxyethylacrylate (HEA) presented inTable 1 indicate the stoichiometric iron phosphate to be an unacceptablematerial.

EXAMPLE 14

The process of Example 1 is followed exactly through the precipitationstep. The resultant flocculent brown precipitate %/wt is then washedusing multiple slurry decant steps. After the final decantation theslurry contains about 6%/wt of the solid catalyst composition, Fe_(x)(PO₄)_(y) X'. Then 300 g of this slurry is mixed with 100 g of acommercially available silica and extruded using conventional, wellknown techniques. The 1/8" diameter extruded catalyst is found to have asurface area of 167 m² /g, a pore volume of 1.2 cc/g, and an averagepore radius of 145Å.

EXAMPLE 15

A solution is prepared by dissolving 69.0 g ferric sulfate hydrate and300.0 g 85% orthophosphoric acid in 197 g of deionized water. Thatsolution is added slowly to a well stirred solution of 146 g of 28%aqueous ammonia in 1245 g of deionized water. The final slurry has a pHof 9.8. The resultant flocculent brown precipitate is separated from themother liquor and washed with copious quantities of deionized waterusing a conventional vacuum filtration apparatus. The product is driedin a forced air oven. The dried product is found to have a BET surfacearea of 1.4 m² /g and has a calculated PO₄ /Fe ratio of 0.88. This veryunsatisfactory low surface area demonstrates that only certain ranges ofcomposition are suitable.

What is claimed is:
 1. A process for preparing hydroxyalkyl esters ofacrylic and methacrylic acid which comprises treating the acrylic ormethacrylic acid with an appropriate alkylene oxide with anon-stoichiometric, amorphous catalyst of the formula:

    M(PO.sub.4).sub.y X'

wherein M is a transition metal, X' is an anionic species, and y is fromabout 0.1 to about 0.9.
 2. The process of claim 1 for preparinghydroxyalkyl esters of acrylic and methacrylic acid which comprisestreating the acrylic or methacrylic acid with an appropriate alkyleneoxide wherein M of the catalyst of claim 1 is selected from Fe⁺³, Cr⁺³and Ce⁺³ at a temperature in the range of from about 30° to about 90° C.3. The process of claim 1 for preparing hydroxyalkyl esters of acrylicand methacrylic acid which comprises treating the acrylic or methacrylicacid with an appropriate alkylene oxide wherein M of the catalyst ofclaim 2 is Fe⁺³ at a temperature in the range of from about 30° to about90° C.
 4. The process of claim 3 for preparing hydroxyalkyl esters ofacrylic and methacrylic acid which comprises treating acrylic ormethacrylic acid with an appropriate alkylene oxide wherein Y in thecatalyst of claim 3 is in the range of 0.2 to 0.6 at a temperature inthe range of from about 30° to about 90° C.
 5. The process of claim 4for preparing hydroxyethyl acrylate.
 6. The process of claim 4 forpreparing hydroxypropyl acrylate.
 7. The process of claim 4 forpreparing hydroxypropyl methacrylate.
 8. The process of claim 4 forpreparing hydroxyethyl methacrylate.